Generally, a cutting insert is used for cutting a workpiece material consisting of iron, nonferrous metal, non-metallic material, etc., while being coupled with a cutting tool mounted to a machine tool.
Such cutting insert generally has an upper surface, a lower surface, and a plurality of lateral surfaces connecting the upper surface and the lower surface. An upper cutting edge is provided between the lateral surfaces and the upper surface, and a lower cutting edge is provided between the lateral surfaces and the lower surface.
As a related art, Korean Registered Patent No. 10-1145491 discloses a cutting insert as illustrated in FIGS. 9 and 10, which is provided with a plurality of grooves 13a, 13b, 13c formed on lateral surfaces to not only reduce cutting load, but also prevent common use of the cutting edges in the same shape for odd-numbered and even-numbered coupling parts 2 of the cutting tool. Such plurality of grooves divide the upper cutting edge 11′ and the lower cutting edge 11″ into a plurality of elements 11a′, 11b′, 11c′, 11d′, 11a″, 11b″, 11c″, 11d″ to induce efficient release of the chips, to minimize contact area with the workpiece material, and to position the cutting insert 10 with accuracy by being inserted into a plurality of position projections 113a, 113b, 113c formed on the coupling part 2 of the cutting tool so as to prevent common use with the odd- and even-numbered coupling parts 2.
Meanwhile, when one side of the upper cutting edge 11′ is broken or deformed during processing, this will result in breakage or deformation of the plurality of grooves 13a, 13b, 13c, in which case the plurality of position projections 113a, 113b, 113c cannot be inserted into the plurality of grooves 13a, 13b, 13c as these are broken or deformed. Accordingly, the cutting insert has to be disposed of, even when all the sides of the lower cutting edge 11″ and the rest sides of the upper cutting edge 11′ are still in good condition for use.